ENIG after SMT assembly

[Nogtail]

I recently placed a JLCPCB order with a slightly unconventional board, where one side is a solid ground plane with its solder mask removed. The other side is more conventional and has been assembled with SMT components. My plan is to use the large flat conductive surface to calibrate some CNC equipment.

Unfortunately I got a message from JLCPCB saying the boards had been damaged during assembly. In the past I haven't had a problem with a bit of comedic damage, so I've asked them to send the boards regardless. As in this case the boards dimensions are important for calibration, I asked if they could remanufacture them. I think there was some miscommunication, as they said they would repeat the ENIG process but not produce new boards.

Is it even possible to ENIG plate fully assembled boards? Are there any problems I should look out for?

Thanks!

[JLCPCB Official]

Hello ,Thank you for your feedback. If necessary, please share your order number with me, and I will check the issue to our support team.

[twospoons]

You expect a PCB to be flat enough to calibrate a CNC? 

[IconicPCB]

Not possible to apply the gold deposit post assembly.

[wraper]

You expect a PCB to be flat enough to calibrate a CNC? 

Depending on what/how it's mounted and how precise it needs to be it may be ok.

[Smokey]

Not possible to apply the gold deposit post assembly.

Sure it is.  It just might not be exactly only where you want it. 

[Nogtail]

You expect a PCB to be flat enough to calibrate a CNC? 

Absolutely no idea if it's going to work, just a proof of concept at this stage. I plan on using it as the first step in a calibration process, so only looking for an accuracy of around 0.5mm. I have a second step to hopefully dial in the accuracy further, but it needs a rough calibration to locate the fiducials correctly.

JLCPCB wasn't able to repeat the ENIG process (no surprise) and ended up remaking the PCB. Fingers crossed it turns up without damage.

[thm_w]

You expect a PCB to be flat enough to calibrate a CNC? 

Flat wise no, but the X and Y dimensions should be very accurate.
Still, seems like an odd way to calibrate a CNC.. Normally you'd just grab a dial indicator, or magnetic/capacitive scales, etc. But 0.5mm is very rough, so maybe.

[abeyer]

But 0.5mm is very rough, so maybe.

Yeah, that sounds like a calibrated metric eyeball is sufficient.